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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
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* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
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* >>> See for details. <<< *
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* Thank you for using FreeRTOS, and thank you for your support! *
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This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details. You should have received a copy of the GNU General Public License
and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
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* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
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*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand. - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
/* High speed timer test as described in main.c. */
/* Scheduler includes. */
#include "FreeRTOS.h"
/* The maximum value the 16bit timer can contain. */
#define timerMAX_COUNT 0xffff
/* The timer 2 interrupt handler. As this interrupt uses the FreeRTOS assembly
entry point the IPL setting in the following function prototype has no effect.
The interrupt priority is set by ConfigIntTimer2() in vSetupTimerTest(). */
void __attribute__( (interrupt(ipl0), vector(_TIMER_2_VECTOR))) vT2InterruptWrapper( void );
/* Incremented every 20,000 interrupts, so should count in seconds. */
unsigned long ulHighFrequencyTimerInterrupts = 0;
/* The frequency at which the timer is interrupting. */
static unsigned long ulFrequencyHz;
void vSetupTimerTest( unsigned short usFrequencyHz )
/* Remember the frequency so it can be used from the ISR. */
ulFrequencyHz = ( unsigned long ) usFrequencyHz;
/* T2 is used to generate interrupts above the kernel and max syscall interrupt
priority. */
T2CON = 0;
TMR2 = 0;
/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
PR2 = ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / ( unsigned long ) usFrequencyHz ) - 1 );
/* Setup timer 2 interrupt priority to be above the kernel priority so
the timer jitter is not effected by the kernel activity. */
/* Clear the interrupt as a starting condition. */
IFS0bits.T2IF = 0;
/* Enable the interrupt. */
IEC0bits.T2IE = 1;
/* Start the timer. */
T2CONbits.TON = 1;
void vT2InterruptHandler( void )
static unsigned long ulCalls = 0;
if( ulCalls >= ulFrequencyHz )
/* Increment the count that will be shown on the LCD.
The increment occurs once every 20,000 interrupts so
ulHighFrequencyTimerInterrupts should count in seconds. */
ulCalls = 0;
/* Clear the timer interrupt. */